I am so sorry your having to deal with this. It is rediculous. The dog needs to be contained on its own property.
Now todays episode really sucks because from the sounds of your last post, it is speculation on what happened. You did not see the culprit from the sounds of the post.
You most definately need to make the area more secure and free ranging seems like it needs to stop until you have something better for them.
Keep a log like the others are telling you. Take pictures and if you catch him in action take pictures of that to. Keep calling animal control and document everything and have proof handy. Sometimes you need to be a very squeaky wheel to get people to pay attention to you. Also, make sure you are in the city guidlines and your chicken outfit is 100% what is allowed in your area.
Do not poison the dog or anything like that as you could end up killing more animals then just him. Paint ball idea is good also. And poison is a torturous way to die.
I have a horible problem with stray dogs in my neighborhood. I only have a 4 ' fense. When my chickens free range in my yard, I am home and I put out one or both of my cocker spaniels out with them. Do they protect the flock from stray dogs? No. But they do sound the alarm if there is a dog, cat, or human around. That gives me time to get outside and see what needs to be done. I am sure next summer when my german shepherd puppy is older I will be able to leave her out to protect them. But, I still will be home while they are loose.
I am very sorry again for the loose of your feathered freinds. Secure their run while fighting the rest of the battle.
The lady with 4 dogs and 4 city chickens